Differential rudder control system



Sept. 8, 1964 F. R. SPECHT DIFFERENTIAL RUDDER CONTROL SYSTEM 3Sheets-Sheet 1 Filed April 3, 1965 u B R r w M 6 i w Qw A 1 P Q A p\ pW.

Sept. 8, 1964 3,147,730

F. R. SPECHT DIFFERENTIAL RUDDER CONTROL SYSTEM Filed April 5, 1963 3Sheets-Sheet 2 FPANZ A. SPEC/47' Sept. 8, 1964 F. R. SPECHT 3,147,730

DIFFERENTIAL RUDDER CONTROL SYSTEM Filed April 3, 1963 3 Sheets-Sheet 5IN VENTOR.

3,147,730 DIFFERENTIAL RUDDER CONTROL SYSTEM Franz R. Specht, NorthMiami Beach, Fla., assignor to Nautec Corporation, New York, N.Y., acorporation of New York Filed Apr. 3, 1963, Ser. No. 270,265 3 Claims.(Cl. 114163) This invention relates to steering controls for marinecraft and more particularly to a control system for twin rudder boatsand the like.

It is an object of the invention to provide a differential ruddercontrol arrangement having particular adaptability to twin screw, twinrudder boats whereby turns are effected by the inboard rudder while theoutboard rudder remains substantially in alignment with the propellerwash.

Other objects of the invention are to provide steering means on a boatwhich permits shorter turning radius, substantially reduces digging inof the bow in turns, substantially reduces tripping action of therudders, and increases the effect of outboard propeller thrust in makingpower turns.

An additional object of the invention is to provide a rudder controlsystem requiring a minimum amount of force to articulate the same.

Briefly one embodiment of the present invention, as adapted for a twinscrew, twin rudder boat having a rudder arm on each rudder extendingnormally in a generally forward direction, includes a steering crankmember disposed between the rudder arms having a pair of crank armsthereon each normally disposed toward a respective one of said rudderarms at an angle of from about 10 to about 45 relative to said rudderarms. The crank arms are about 25% shorter than the rudder arms and areeach interconnected with its respective rudder arm by a mechanicallinkage such as a connecting rod or the like. An actuating arm isincluded on said steering crank member below the plane of the crank armswhich is interconnected by suitable linkage means with the helm foractuating the rudder mechanism to effect directional control of theboat.

With such an arrangement as described above each rudder can be swungthrough a rather wide angle in an inboard turn and only through arelatively small angle in an outboard turn.

Other objects and features of the invention will be apparent in thefollowing specification and claims and in the drawings in which:

FIG. 1 is an isometric view of one embodiment of the invention;

FIG. 2 is a reduced plan view of the apparatus shown in FIG. 1;

FIG. 3 is a section taken along lines 3--3 of FIG. 2;

FIG. 4 is a simplified schematic diagram of an arrangement according tothe invention;

FIG. 5 is a simplified schematic diagram of another arrangementaccording to the invention;

FIG. 6 is a schematic diagram of a modified form of the invention; and

FIG. 7 is another simplified schematic diagram of another arrangementaccording to the present invention.

Referring now to the drawings, and in particular FIGS. l-3, oneembodiment of the differential control system of the present inventionis shown and designated generally by reference numeral 10. It iscomprised of steering crank member 11 comprising bracket 12 having abase plate 13 which is mounted amidships on a transverse bulkhead 14disposed adjacent transom 15 of a boat designated generally by referencenumeral 16. Extending in a forward direction from base plate 13 areupper and lower arms 17, 18 having respective mounting hubs 19,

United States Patent I 3,147,730 Patented Sept. 8, 1964 "Ice 20 at theirouter ends disposed in vertical axial alignment. Said hubs 19, 20 carryrespective bushing members 21, 22 in which is journaled shaft member 23.Mounted on shaft 23 between hubs 19, 20 and adjacent hub 19 isbifurcated crank member 24 having arms 25, 26 extending in respectiveangular outboard directions. Also mounted on shaft 23 between crankmember 24 and hub 20 is actuating arm 27.

Steering crank member 24 and actuating arm 27 are fixed to shaft 23 bysuitable means including pinch bolts 28 and are directly connected toshaft 23 by longitudinal key 29.

Boat 16 has twin rudders 30, 31 having conventional mountings 32, 33including forwardly extending rudder arms 34, 35. Crank arms 25, 26 onsteering crank member 24 are substantially of equal length to rudderarms 34, 35 and are disposed at respective acute angles, e.g. about 10to about 45, relative to said rudder arms 34, 35. Outer ends 36, 37 ofcrank arms 25, 26 are interconnected with outer ends 38, 39 of rudderarms 34, 35 by connecting rods 40, 41 and actuating arm 27 isinterconnected with pitman arm 42, disposed adjacent one side of thehull and forward of rudder arm mounting means 33, by connecting rod 43.Pitman 42 is further connected with the forward steering mechanism (notshown) of the craft by suitable linkage means such as gear box 44 androtary shaft 44a. Pitman arm 42 is disposed generally parallel to theactuating arm 27 in order to transmit turning force to the actuating arm27 at an approximate angle of 90. However, actuating arm 27 need nothave any specific angular relationship with respect to pitman arm 42.All that is required is that the crank member 24 with its actuating arm27 be actuated up to about 45 in both clockwise and counterclockwisedirections.

Rotary movement e.g. counterclockwise (as viewed in FIG. 2) of rotaryshaft 44a correspondingly turns pitman arm 42 counterclockwise about itspivot 45 and through connecting rod 43 transmits corresponding angularmovement to actuating arm 27, thereby pivoting crank arm 25 and throughconnecting rod 40 pivoting rudder arm 34 in a counterclockwise directionto move rudder 30 counterclockwise as viewed in FIG. 2 representing thestarboard turn of the heat When moving in a forward direction.Simultaneously through crank arm 26, connecting rod 41, and rudder arm35, rudder 31 is pivoted in a counterclockwise direction. However, inview of the angular disposition of crank arms 25, 26 relative to rudderarms 34, 35 (see FIGS. 4 and 5) inboard rudder 31 is pivoted in arelatively wide angle, e.g. 40, whereas outboard rudder 30 is pivotedonly a relatively small amount, e.g. about 11. If crank arms 25, 26 areabout 25 shorter than rudder arms 34, 35 (see FIG. 5) then outboardrudder 30 would turn only about 2 or 3 when inboard rudder 31 is turnedabout 40 (see dotted lines). It is to be understood that, due to thegeometry of the rudder control system described above, when making aturn to port with the craft moving in a forward direction, rudder 30becomes the inboard rudder and rudder 31 the outboard rudder andrelative movements of the two are reversed in a similar fashion.

In a modification of the invention shown in FIG. 6 rudders 30 and 31 areinstalled at about an angle of 15 from the vertical with their lowerportions 46, 47 extending angularly outwardly. In this installation balljoints (not shown) are added to the rudder mounting means 32, 33, whichwould be apparent to the man skilled in the art, in order to make theactuation of the rudders feasible. With this added feature the turningradius of the craft is shortened even more than with the differentialcontrol system described above by controlling the toe of the rudders.

By shortening the connecting rods 40, 41 as shown in FIG. 7 the rudderscan be toed in or out and the running attitude of the boat can bealtered, the rudders then acting partially as elevators. With theinclusion of variable length connecting rods 40, 41 the attitude of thecraft can be altered while under way. The variable linkage can either bemechanical or hydraulic with the control placed at the helm.

In the above arrangement steering power is always placed on the crankarms and not the rudder arms. The interconnection between the helm andsteering crank member can be by any known means such as mechanical,hydraulic or push-pull cable. Due to the fact that essentially only onerudder is utilized in turning, less force is required to actuate themechanism thereby placing less strain on the steering gear from thesteering wheel to the actuating arm at the steering crank member. Thispermits the use of push-pull cable in the steering mechanism Whichotherwise might not be adequate.

v The various parts of the above mechanism may be made of the usualmaterials of choice for marine equipment of this type. The rudder armsmay be disposed in normally forward directions as shown in the disclosedembodiment or may be used in other modified arrangements, e.g., disposednormally rearwardly or in other preselected directions as desired solong as the advantageous selective actuation of the rudders can beachieved.

It is thus seen that the present invention provides a differentialrudder control system particularly adapted to twin screw, twin rudderboats which achieves all of the aforementioned objects.

It is to be understood that changes and additions may be made by thoseskilled in the art without departing from the scope and spirit of theinvention.

What is claimed is:

1. In a twin screw twin rudder boat a diiferential rudder actuatingmechanism for articulating the inboard rudder in a turn whilemaintaining the outboard rudder in substantially neutral positioncomprising a rudder arm on each rudder extending normally in a forwarddirection, a steering crank member disposed between said rudder arms andhaving a pair of crank arms each normally disposed toward a respectiveone of said rudder arms at an angle of from about 10 to about degreesrelative to said rudder arms, said crank arms being about 25 shorterthan said rudder arms, linkage means interconnecting each crank arm withits respective rudder arm, and means on said steering crank member forinterconnection with the steering means of said boat.

2. In a twin screw twin rudder boat a diiierential rudder actuatingmechanism for articulating the inboard rudder in a turn whilemaintaining the outboard rudder in substantially neutral positioncomprising a pair of rudders mounted on the hull of said boat at anangle of about 15 from the vertical, a rudder arm on each rudderextending normally in a forward direction, a steering crank memberdisposed between said rudder arms and having a pair of crank arms eachnormally disposed to ward a respective one of said rudder arms at anangle of from about 10 to about 45 degrees relative to said rudder arms,said crank arms being about 25% shorter than said rudder arms, linkagemeans interconnecting each crank arm with its respective rudder arm, andmeans on said steering crank member for interconnection with thesteering means of said boat.

3. In a twin screw twin rudder boat a diiferential rudder actuatingmechanism'for articulating the inboard rudder in a turn whilemaintaining the outboard rudder in substantially neutral positioncomprising a rudder arm on each rudder extending normally in a forwarddirection, a steering crank member disposed between said rudder arms andhaving a pair of crank arms each normally disposed toward a respectiveone of said rudder arms at an angle of from about 10 to about 45 degreesrelative to said rudder arms, said crank arms being about 25% shorterthan said rudder arms, connector arms interconnecting the end of eachcrank arm with the end of its respective rudder arm, and means on saidsteering crank member for interconnection with the steering means ofsaid boat.

References Cited in the file of this patent UNITED STATES PATENTS1,717,286 Ward 2 June 11, 1929 FOREIGN PATENTS 277,022 Great BritainNov. 3, 1927

1. IN A TWIN SCREW TWIN RUDDER BOAT A DIFFERENTIAL RUDDER ACTUATINGMECHANISM FOR ARTICULATING THE INBOARD RUDDER IN A TURN WHILEMAINTAINING THE OUTBOARD RUDDER IN SUBSTANTIALLY NEUTRAL POSITIONCOMPRISING A RUDDER ARM ON EACH RUDDER EXTENDING NORMALLY IN A FORWARDDIRECTION, A STEERING CRANK MEMBER DISPOSED BETWEEN SAID RUDDER ARMS ANDHAVING A PAIR OF CRANK ARMS EACH NORMALLY DISPOSED TOWARD A RESPECTIVEONE OF SAID RUDDER ARMS AT AN ANGLE OF FROM ABOUT 10 TO ABOUT 45 DEGREESRELATIVE TO SAID RUDDER ARMS, SAID CRANK ARMS BEING ABOUT 25% SHORTERTHAN SAID RUDDER ARMS, LINKAGE MEANS INTERCONNECTING EACH CRANK ARM WITHITS RESPECTIVE RUDDER ARM, AND MEANS ON SAID STEERING CRANK MEMBER FORINTERCONNECTION WITH THE STEERING MEANS OF SAID BOAT.